Microwave polymerization system for dentistry

Abstract

A microwave polymerization system for dentistry utilizes specifically controlled microwave energy to cure polymer materials so as to produce dental prosthetics, such as dentures, bridges and crowns, that are made in an extra-oral setting such as a dental laboratory or dental office, and to create dental composites for fillings and veneers that are used in an intra-oral setting directly in the patient's mouth. Unlike the microwave energy delivered by commercial microwave ovens which is controlled by pulsing a maximum voltage pulse on and off at a given duty cycle, the system utilizes metered and controlled microwave energy that is preferably continuous and voltage controlled, and regulates the application of this microwave energy by use of various feedback and control mechanisms. The metered and controlled microwave energy enables a higher degree of conversion of monomers into polymer chains in the polymerization process, thereby enhancing the physical and biocompatibility characteristics of both dental prosthetics and dental composites made from polymers. In an extra-oral embodiment, gaseous pressure is applied to the resin matrix during the polymerization process to further enhance the polymerization process. In an intra-oral embodiment, the polymerization process can be accomplished with less overall energy and with composite-matrices that maximally absorb the microwave energy so as to reduce heating of adjacent tissue.

What is claimed is:  
     
       1. A microwave polymerization system for polymerizing dental prosthetics and dental composites formed of a resin matrix comprising: 
       a source of a substantially constant frequency microwave energy;  
       an antenna defining a substantially constant volume space during an application of the microwave energy to the resin matrix;  
       a waveguide connected to the source of microwave energy and to the antenna to deliver microwave energy to the antenna; and  
       a control system operably connected to the source of microwave energy that meters and controls application of the microwave energy to the resin matrix in response to sensing of a transmitted microwave energy and a reflected microwave energy so as to enhance a degree of polymerization and cross-linking of the resin matrix when polymerized into a dental prosthetic or dental composite.  
     
     
       2. The system of  claim 1  wherein the antenna is in the format of a cavity, defined by continuous walls, having at least one opening therein to permit insertion and removal of at least one flask containing a dental prosthetic made of a resin matrix that is to be microwave polymerized. 
     
     
       3. The system of  claim 2  further comprising a gas pressurization system that applies a pressurized gas to the flask during the application of microwave energy. 
     
     
       4. The system of  claim 3  further comprising a material injection system that introduces additional resin matrix into the flask during the application of microwave energy. 
     
     
       5. The system of  claim 4  further comprising means for rotating the flask within the cavity and including rotatable couplers for connecting the gas pressurization system and the material injection system to the flask. 
     
     
       6. A method of polymerizing dental prosthetics and dental composites formed of a resin matrix comprising: 
       providing a source of a substantially constant frequency microwave energy;  
       applying the microwave energy through an antenna to the resin matrix as the resin matrix is positioned in a cavity having a substantially constant volume; and  
       controlling application of the microwave energy to the resin matrix using a control system that control the operation of the source of the microwave energy using control and feedback mechanisms so as to enhance a degree of polymerization and cross-linking of the resin matrix when polymerized into a dental prosthetic or dental composite.  
     
     
       7. The method of  claim 6  further comprising the step of applying pressure to the resin matrix during the application of microwave energy. 
     
     
       8. The method of  claim 7  further comprising the step of introducing additional material to the resin matrix during the application of microwave energy. 
     
     
       9. The method of  claim 6  wherein the control system is operated in response to a sensing of a transmitted microwave energy and a reflected microwave energy applied to the resin matrix. 
     
     
       10. The method of  claim 6  wherein the control system is operated by varying at least a voltage applied to the source of microwave energy as the resin matrix is polymerized into a dental prosthetic or dental composite. 
     
     
       11. A microwave polymerization system comprising: 
       a source of a substantially constant frequency microwave energy;  
       an antenna in the front of a cavity, defined by fixed walls, having at least one opening therein to permit inspection and removal of at least one flask containing a dental prosthetic form having therein a resin matrix;  
       a waveguide connected to the source of microwave energy and to the antenna to deliver microwave energy to the antenna; and  
       a control system operably connected to the source of microwave energy that meters and controls application of the microwave energy to the resin matrix by varying at least a voltage applied to the source of microwave energy as the resin matrix is polymerized into a dental prosthetic;  
       wherein the at least one opening is closed during application of the microwave energy and the cavity defines a substantially constant volume during application of the microwave energy.  
     
     
       12. The system of  claim 11  further comprising a gas pressurization system that applies a pressurized gas to the flask during the application of microwave energy. 
     
     
       13. The system of  claim 12  further comprising a material injection system that introduces additional resin matrix into the flask during the application of microwave energy. 
     
     
       14. The system of  claim 13  further comprising means for rotating the flask within the cavity and including rotatable couplers for connecting the gas pressurization system and the material injection system to the flask.